Tooth for bridgework and crown-work.



. H. B. GREGORY.

TOOTH POR BRIDGBWORK AND CROWN WORK.

APPLICATION FILED DEG. 22, 1910.

Patented Dec. 5, 1911..

Ill/ll.

CuLuMBIA PLANoouAPH CD.. WAsumoroN. n. c.

HARRY B. GREGORY, 0F LANSING, MICHIGAN.

TOOTH FOR BRIDGEWORK AND CROWN-WORK.

Specification of Letters Patent.

Application filed December 22, 1910.

Patented Dec. V5, 1911.

Serial No. 598,737.

To all whom 'it may concern:A

Be it known that I, HARRY B. GREGORY, a citizen of the United States, residing at Lansing, in the county of Ingham andState of Michigan, have invented certain new and useful Improvements in Teeth for Bridgework and Crown-Work; and I do declare the following to be a full, clear, and eXact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to improvements in artiiicial teeth and has special reference to teeth employed in bridge work and crown work.

The object of the invention is to provide a tooth especially adapted for use in crown and bridge work by which a secure fasten- .ing of the tooth to the bridge will be provided.

A further object of the invention is to provide a tooth which may be readily removed from thebridge and replaced by duplicate should the tooth be broken and which, when in position, will be reinforced by a solid metallic body at its lower end so that the cracking or breaking of the tooth in use will be avoided.

With these stated objects and such other` incidental objects as will hereinafter appear in view, the invention consists in certain novel features of the device illustrated in the accompanying drawings which will be hereinafter iirst fully described and then more particularly pointed out in the appended claims.

In the annexed drawings Figure 1 is a front elevation of 'a portion of a bridge with my improved teeth in position thereon; Fig. 2 is a rear elevation of the same; Fig. 3 is a front elevation of the metal backing; Fig. 4 is a horizontal section taken on the line 4-4 of Fig. 2; Fig. 5 is a detail perspective view of a single tooth; Fig. 6.

is a vertical, section on the line 6-6 of Fig. 1; Fig. 7 is a view similar to Fig. 6 but showing a slightly different form of tooth; and Fig. 8 is a horizontal section through a bridge employing my improved tooth and showing the backing produced by casting in one piece.

In carrying out my invention, I employ an artificial tooth 1 which may be of any desired shape according to the position in which'it is to be used and which will preferably be formed of porcelain as is the usual practice. The' upper end of the tooth is beveled downwardly toward therear side of the same, as indicatedv at 2, so as to simulate the shape of a natural tooth and to fit comfortably against the gum. On the rear side of the tooth, I provide a large locking lug 3, the side edges of which are preferably at right angles to the vertical plane of the tooth, while the upper and lower ends or edges of the lug are beveled downwardly and rearwardly as clearly shown in Figs. 6 and 7, thereby producing an overhanging lip 4 which is adapted to lockingly engage the bridge as will presently appear. Below this overhanging lip 4,- the rear side of the tooth is beveled slightly forwardly, as shown at 5, to provide a biting edge for the tooth and, ifnecessary, in order to give the necessary strength and reinforcement to the tooth, a small depression 'or cavity 6 may be'formed in the rear side of the tooth immediately adjacent the overhanging lip 4, as will be readily understood on reference to Figs. 5 and 6.

In making a bridge in which my improved tooth is to be employed, the' tooth or teeth to be supplied to the patientare first fitted to t-he mouth or model so as to obtain the necessary lit and sameness of appearance between the artificial andthe natural teeth and theartificial teeth are then placed in and held by a mold of waX as is the usual practice. A backing plate 7 of gold or other metal is then worked into intimate contact with the rear sides of the teeth by swaging or otherwise and the said backing plate will of course conform to the shape of the lugs on the back of the teeth and will present an upwardly inclined shoulder 8 adapted to fit `against the overhanging lip 4 and form a dove-tailed engagement with the tooth as will be readily understood. The backing plate may then be removed from the teeth and gold solder flowed over the same so as to firmly unite the separate teeth of the backing and constitute a means for joining the bridge to a suitable anchor provided on the natural teeth. The backing plate will, furthermore, lit into the depression or cavity 6 so as to form a rib or projection 9 and this rib or projection will further aid in holding the tooth in its proper position. If

the item of expense is to be carefully c011- sidered, the backing plate may be omitted and the gold vsolder 10 flowed directly upon the teeth, as indicated in Figs. 7 and 8, the solder, of course, shaping itself to the shape of the teeth and the lugs on the bac-ks of the same so that the teeth will be firmly held in place.

It will be Observed that in the completed bridge, there is a considerable body of metal below the Overhanging lip 4, as shown at 11, and this body of metal is worked down slightly below and under the lower edge of the tooth, as shown at 12, so that a very strong biting surface will be provided and the breaking or cracking Of the tooth through its ordinary use will be thereby avoided and almost entirely eliminated. The lug 3 on the back of the tooth provides a large surface tO engage the backing or bridge and its angular formation will effectually prevent the twisting of the tooth upon the bridge. The Overhanging lip and the upwardly inclined shoulder of the tooth and the backing or bridge respectively permit the tooth to be readily removed from the bridge should it be necessary to substitute a new tooth at any time and also so engages the tooth with the bridge that the Ordinary use of the teeth in biting will not tend to dislodge the teeth but, on the contrary, will serve to more firmly engage them with the bridge.

My invention will permit the dentist to perform bridge work rapidly and ineXpen sively and at the saine time the product when placed in the mouth of the patient will have an attractive appearance and will firmly retain the teeth in their proper position.

Having thus described my invention, what I claim is l. An artificial tooth provided on its rear side with an angular lug having its upper and lower ends beveled downwardly and rearwardly.

2. An artificial tooth provided on its rear side with a rearwardly and downwardly projecting lug and provided in its rear surface below the said lug with a backing receiving cavity.

3. The combination with an artificial tooth having a rearwardly projecting lug on its rear side, said lug having an overhanging lower end, and a backing or bridge fitting around the said lug and to the rear side of the tooth and depending slightly below and under the lower end of the tooth.

4. An artificial tooth provided with a rearwardly projecting lug the under side of which is beveled downwardly and rearwardly, the rear surface of the tooth below the lug being beveled downwardly and Outwardly.

5. An artificial tooth provided with a rearwardly projecting lug the under side of which is beveled downwardly and rearwardly, the rear surface of the tooth below the lug being beveled downwardly and Outwardly and provided adjacent to said underside Of the lug with a curved undercut cavity.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

HARRY R. GREGORY.

Witnesses:

L. O. HILTON, R. W. BISHOP.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

